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Biomedical subjects

Yoshihiro Okamoto

Publications and source records attributed to Yoshihiro Okamoto.

14 recordsLinked to original sources
PubMed2005

Serum evaluation of the balance between soluble interleukin-2 and interleukin-4 receptors.

To elucidate the usefulness of the simultaneous analysis of the multiple kinds of soluble cytokine receptors, we determined both the soluble interleukin 2 receptor (sIL-2R, Th1-type cytokine receptor) and the soluble interleukin 4 receptor (sIL-4R, Th2-type cytokine receptor) levels in the sera of healthy subjects as reference values and preliminarily applied to evaluate the patients with diarrhea positive (D+) hemolytic uremic syndrome (HUS) as the diagnostic parameter of the severity. Both sIL-2R and sIL-4R levels in the sera of healthy children were significantly higher than those of healthy adults (p<0.01). The serum sIL-2R level of the patients with severe HUS (n=4) was higher than that of the patients with mild/moderate HUS (n=6) at the initial stage (p<0.01) or healthy children (n=51, p<0.01). Whereas, the serum sIL-4R level of both the severe and mild/moderate groups was lower than that of the healthy control children, although there was no significant difference among the three groups. Namely, the soluble receptor balance (sIL-2R/sIL-4R) in the patients with severe HUS may shift. We considered that the evaluation of the balance between soluble cytokine receptors might be informative for the evaluation of the immune states, as well as the conventional cytokine balance (Th1/Th2).

Adolescent↗
PubMed2005

Differentiation from embryonic stem cells to vascular wall cells under in vitro pulsatile flow loading.

This study evaluated the possibility of differentiation from embryonic stem (ES) cells to vascular wall cells by physical (mechanical) stress loading in vitro. A cell mixture containing Flk1-positive cells (ca. 30%) derived from murine ES cells was added to a compliant microporous tube made of segmented polyurethane. The compliance of the tube was close to that of the human artery [the stiffness parameter (beta) = 57.2 (n = 5, SD < 5%)]. The luminal surface of the tube was fully covered with the cells by preincubation for two days in the presence of vascular endothelial growth factor (VEGF). After 2 days of additional incubation without VEGF under static conditions, layering of the grown cells, mostly smooth muscle actin (SMA)-positive cells, was observed only on the luminal surface of the tube. The cells were flat, polygonal, and randomly oriented. On the other hand, after a 2-day incubation under a weak pulsatile flow simulating the human venous systems [wall shear stress (WSS) from -0.98 to 2.2 dyn/cm(2); circumferential strain (CS) 4.6-9.6 x 10(4) dyn/cm(2)] without VEGF, cells in the superficial layer were regularly oriented in the direction of the pulsatile flow. The oriented cells exhibited endothelial-like appearance, indicating that they were platelet endothelial cell adhesion molecule 1 (PECAM1)-positive. In addition, the cells growing into the interstices in the deeper layer showed smooth muscle-like appearance, indicating that they were SMA-positive. Differentiation to two different cell types and segregation of incorporated ES cells may be simultaneously encouraged by the combination of WSS and CS. It is expected that the monobloc building of hierarchically structured hybrid vascular prostheses composed of several vascular wall cell types is possible by physically synchronized differentiation of ES cells.

Actins↗
PubMed2005

Development of sutureless vascular connecting system for easy implantation of small-caliber artificial grafts.

A novel sutureless vascular connecting system, an assembly with a delivery rod, an introducing sheath, and a connecting device, was developed for easy implantation of small-caliber vascular grafts less than 2 mm in internal diameter. A microporous stainless tube (length 2 mm, external diameter 1.6 mm, wall thickness 65 microm, pore diameter 400 microm, pore-to-pore distance 500 microm) was designed to serve as a connecting device. The feasibility of the system was tested using two types of preliminary animal experiments. One animal model consisted of graft implantation into the rat abdominal aorta (1.5 mm in diameter). The connecting device was inserted into the proximal and distal ends of the aorta through the introducing sheath by pushing the delivery rod with the connecting device placed over it. Subsequently, the aortic segments were inserted into both ends of model grafts made of segmented polyurethane (1.8 mm in internal diameter) and were fixed with banding silk threads from the exterior. The procedure was completed within 20 min without requiring specialized microsurgery techniques. Blood leakage and obstruction did not occur. The second model consisted of an end-to-end anastomosis between rabbit common carotid arteries (2 mm in diameter), which was performed within several minutes of blood flow interruption. Scanning electron microscopy demonstrated that the luminal surface of the device was fully covered with endothelial cells (ECs) after 1 week as a result of transluminal ingrowth of native ECs through the micropores in the device. This endothelialization may prevent early thrombus-induced occlusion. This simple and "easy-to-learn" technique will promote the development of small-caliber arterial grafts, and furthermore, it may have potential for clinical application.

Anastomosis, Surgical↗
PubMed2005

Age-dependent decrease in serum transforming growth factor (TGF)-beta 1 in healthy Japanese individuals; population study of serum TGF-beta 1 level in Japanese.

Transforming growth factor-beta1 (TGF-beta1), a multi-functional cytokine, is involved in regulating a variety of cellular activities and the serum/plasma TGF-beta1 level is altered with various diseases. However, most published reports have described adult patients, and so we investigated the clinical significance of serum TGF-beta1 level in pediatric patients. The diagnostic application of the measurement of serum TGF-beta1 level depends critically on the control value, however, there is no information on the control value of serum TGF-beta1 for children. In the present study, we determined the serum TGF-beta1 level of healthy Japanese children as a control value with enzyme-linked immunosorbent assay (ELISA). The serum TGF-beta1 level of children (0-14 years old) was significantly higher than that of adults (over 15 years old) (p < 0.01). Thus, it is recommended that when the serum TGF-beta1 levels of patients are evaluated, they should be compared with those of age-matched controls.

Adolescent↗
PubMed2005

[Development of the method for analysis of the cytokine balance shift associated with diseases].

A dual-color enzyme-linked immunospot (ELISPOT) assay enabled us to analyze three types of cytokine-secreting cells simultaneously. T helper (Th) cells can be subdivided into at least two distinct functional subsets based on their cytokine secretion profiles. The first type of clones (Th1) produces interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), but not IL-4 or IL-5. The second type of clones (Th2) produces IL-4 and IL-5, but not IL-2 or IFN-gamma. Furthermore, the presence of the third type (Th0) of cell, which is a precursor of Th1 or Th2 cells, has been demonstrated to produce both Th1- and Th2-type cytokines. The dual-color ELISPOT assay was developed to differentiate these three subtypes of Th cells in an identical well. In the system, the red spots corresponding to IL-2-secreting cells (Th1) were developed with horseradish peroxidase and aminoethylcarbazole/H(2)O(2). The light-blue spots corresponding to IL-4-secreting cells (Th2) were developed with alkaline phosphatase and Vector blue (chromogenic substrate for alkaline phosphatase). The mixed-colored (indigo) spots corresponding to both types of cytokine-secreting cells (Th0-cells) were developed with both chromogenic substrates. With this system, we could detect the IL-2- and/or IL-4-secreting cells simultaneously in a murine spleen cell or human peripheral mononuclear cell preparation.

Animals↗
PubMed2005

Dual-color ELISPOT assay for analyzing cytokine balance.

A dual-color enzyme-linked immunospot (ELISPOT) assay enabled us to analyze three kinds of cytokine-secreting cells simultaneously. T helper (Th) cells can be subdivided into at least two distinct functional subsets based on their cytokine secretion profiles. The first type of clones (Th1) produces interleukin (IL)-2 and interferon (IFN)-gamma but not IL-4 or IL-5. The second type of clones (Th2) produces IL-4 and IL-5 but not IL-2 or IFN-gamma. Furthermore, the presence of the third type (Th0) cell, which is a precursor of Th1 or Th2 cells, has been demonstrated to produce both Th1- and Th2-type cytokines. The dual-color ELISPOT assay is developed to differentiate these three subtypes of Th cells in an identical well. In the system, the red spots corresponding to IL-2-secreting cells (Th1) were developed with horseradish peroxidase and amino-ethyl-carbazole/H2O2. The light blue spots corresponding to IL-4-secreting cells (Th2) were developed with alkaline phosphatase and Vector blue (chromogenic substrate for alkaline phosphatase). The mixed colored (indigo) spots corresponding to both kinds of cytokine-secreting cells (Th0 cells) were developed with both chromogenic substrates. With this system, we could detect the IL-2- and/or IL-4-secreting cells simultaneously in a murine spleen cell or human peripheral mononuclear cell preparation.

Adult↗
PubMed2004

17alpha-hydroxylase/C17-20 lyase cytochrome P450 mRNA expressions and enzyme activities during the development of arthritis in collagen-induced arthritis mice.

In our previous study, we have investigated the serum levels of dehydroepiandrosterone (DHEA) in type II collagen (CII)-induced arthritis (CIA) mice. During the study, we found that in normal control mice, serum levels of DHEA in the latter half of the experimental period (13-16 weeks old) were significantly lower than those at the beginning of the experiment (10 weeks old). However, in CIA mice, such decreases were not observed by CII treatment. To examine the cause of the retention of DHEA during the development of arthritis in CIA mice in this study, 17alpha-hydroxylase/C17-20 lyase P450 (CYP17) mRNA expressions were measured by real time RT-PCR and the CYP17 enzyme activities were investigated in the liver and testis on days 6, 13, 28 and 48 after CII treatment in DBA/1J mice. There were no significant differences of CYP17 expressions in the liver between control and CIA mice at each experimental day, while a significant increase of expression in the testis of CIA mice was observed on day 48. On the other hand, CYP17 enzyme activities on days 28 and 48 in testis microsome (Mc) from the CIA mice were significantly higher than those of the control on the same day, while no significant differences of activities in liver Mc were observed between the CIA and control mice. These findings suggested that the cause of the retention of DHEA on days 28 and 48 after CII treatment may be the increase of CYP17 expression and the enzyme activities in the testis.

Animals↗
PubMed2004

Anthropometric, lifestyle and biomarker assessment of Japanese non-professional ultra-marathon runners.

BACKGROUND: Anthropometric characteristics, lifestyle, and baseline biological markers of Japanese non-professional ultra-marathon runners have not been fully assessed. METHODS: We evaluated anthropometric characteristics, lifestyle, and baseline biological markers of 180 Japanese amateur ultra-marathon runners (144 males [mean age: 50.5 +/- 9.4 (standard deviation) years] and 36 females [48.9 +/- 6.9]), and compared them with those of participants in a community heath check-up program and with the figures in the literature. We furthermore evaluated baseline blood indices according to monthly running distance with analysis of variance adjusted for age, body mass index, smoking and alcohol drinking habits. RESULTS: The ultra-marathon runners demonstrated more favorable values for body mass index and bone density, and the proportion of smoking, and undertaking physical activity (for both sexes), eating breakfast (for males), and having daily bowel movements (for females), while greater proportion of alcohol drinking habit (for both sexes), than the comparison group. Average monthly running distances and standard deviations (km) were 257.2 +/- 128.9 for males and 209.0 +/- 86.2 for females. Male runners possessed beneficial markers, including lowered triglyceride and elevated high-density lipoprotein cholesterol, and their values showed hockey-stick (or inverse hockey-stick) patterns depending on their monthly running distance. Some subjects running more than 300 km/month exhibited signs of an over-reaching/training syndrome, including somewhat lowered hemoglobin, ferritin and white blood cell count, and elevated creatine kinase and lactate dehydrogenase. CONCLUSIONS: Together with a desirable lifestyle, Japanese non-professional ultra-marathon runners with vigorous exercise habit demonstrated a preferable health status according to biological indices.

Adult↗
PubMed2003

Denaturing high performance liquid chromatography analysis of the DPYD gene in patients with lethal 5-fluorouracil toxicity.

Dihydropyrimidine dehydrogenase (DPD) enzyme deficiency is a pharmacogenetic syndrome with possible fatal outcome following 5-fluorouracil (5-FU) treatment. Several studies examining the molecular basis for DPD deficiency have identified over 30 sequence variations in the DPYD gene (which codes for the DPD enzyme). Our laboratory has recently developed and validated a denaturing high performance liquid chromatography method capable of identifying both known and unknown sequence variations in the DPYD gene. In the present study, we used this denaturing high performance liquid chromatography approach to examine the DPYD genotype of three patients who experienced lethal toxicity after administration of 5-FU. DPD enzyme activity could only be measured in one patient before death and demonstrated that lethal toxicity can occur in a partially DPD-deficient individual. Multiple heterozygous sequence variations (both known and unknown) were detected in all three patients including the novel variants 545T>A, M182K and 2329G>T, A777S. We conclude that (a) lethal toxicity can occur in partially DPD-deficient individuals after administration of 5-FU and is not exclusive to profoundly DPD-deficient individuals as suggested previously, (b) the complicated heterozygote genotype seen in these patients, combined with DPD deficiency being an autosomal codominant inherited syndrome, precludes the use of simple genotyping assays that identify only one or two mutations as a method for identifying DPD-deficient individuals; and (c) these multiple heterozygote genotypes (which are more difficult to accurately characterize) may be responsible for some of the conflicting reports which suggests a lack of correlation between phenotype and genotype.

Aged↗
PubMed2003

Participation of endogenous dehydroepiandrosterone and its sulfate in the pathology of collagen-induced arthritis in mice.

We have investigated the serum levels of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) in type II collagen (CII)-induced arthritis (CIA) DBA/1J mice, an experimental model of human rheumatoid arthritis (RA). Serum levels of DHEA and DHEAS were measured by EIA and GC/MS, respectively. Sera were obtained from the mice on day 6, 13, 28 and 48 after the CII treatment. The disease onset of CIA was observed from day 28 (7%) to day 48 (80%) after CII immunization. The serum concentration of DHEA on day 13 did not differ from that on day 6 in CIA mice and untreated controls. Serum levels of DHEA on day 28 and 48 were significantly low compared with those on day 6 in controls. However, in CIA mice, DHEA levels on day 28 and 48 were not decreased from those on day 6. No difference in the serum DHEAS level on day 13 compared with day 6 was observed in either control or CIA mice. A significant decrease of DHEAS levels on day 28 and 48 compared with day 6 was found in both groups. The time point for the retention of DHEA in CIA mice, day 28 and day 48, coincided with the disease onset of CIA. In conclusion, endogenous DHEA may be produced as a result of physiological response for the protection against CIA.

Animals↗
PubMed2002

A high-throughput denaturing high-performance liquid chromatography method for the identification of variant alleles associated with dihydropyrimidine dehydrogenase deficiency.

Dihydropyrimidine dehydrogenase (DPD) is the initial, rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU). A pharmacogenetic syndrome has been described in which DPD-deficient patients are at risk for toxicity following administration of 5-FU. To date, there are at least 21 previously described mutations and/or polymorphisms that have been associated with DPD deficiency. In this study we describe the development of a highly specific, sensitive, inexpensive, and robust denaturing HPLC (DHPLC) method for rapidly identifying sequence variations (mutations and/or polymorphisms) in the gene (DPYD) that codes for the DPD enzyme. DHPLC conditions were optimized at three temperatures for analysis of the 23 exons of the DPYD gene using 25 amplicons representing the entire coding sequence, including all intron/exon boundaries (splice sites). Resolution of all 25 amplicons at the optimized temperature can be performed in 4.2 h. All 21 previously described sequence variations (mutations and/or polymorphisms) were prepared using site-directed mutagenesis from the wild-type DPYD gene, confirmed by sequence analysis, and subsequently resolved by DHPLC using the optimized conditions. These analyses generated reference chromatogram patterns for all known sequence variations previously encountered in DPD-deficient patients. In order to examine the utility and sensitivity of this approach, samples from patients with known sequence variations in the DPYD gene were analyzed. This DHPLC technique resolved 100% of the known DPYD sequence variations and differentiated between homozygous and heterozygous genotypes. We conclude that this DHPLC method is a highly specific and sensitive technique for rapidly detecting known sequence variations in the DPYD gene. In addition, this approach can be used to identify currently unrecognized unknown sequence variations in the DPYD gene and should be useful in future pharmacogenetic studies examining DPD deficiency.

Alleles↗
PubMed2002

Anti-arrhythmic efficacy of nifekalant hydrochloride, a pure class III anti-arrhythmic agent, in patients with healed myocardial infarction and inducible sustained ventricular tachycardia.

In recent clinical trials, class III anti-arrhythmic drugs were found to reduce arrhythmic deaths in patients after myocardial infarction. The purpose of this study was to assess the electrophysiologic properties and anti-arrhythmic efficacy for inducible sustained ventricular tachycardias (VTs) of the pure class III agent nifekalant hydrochloride (MS-551) in comparison with those of procainamide. Programmed ventricular stimulation of up to three extra stimuli was performed for induction of VTs. Effective refractory period (ERP) of the ischemic zone and normal zone was also measured before and after nifekalant. Nifekalant and procainamide suppressed sustained VT induction in four of 15 patients and in six of 15 patients, respectively (p = NS). Sinus cycle length, PR interval, and QRS duration were not changed, but QT and QTc intervals were significantly increased with nifekalant (p < 0.01). Ventricular ERP also increased, whereas there were no significant differences in the increase of ERP between the ischemic and normal zones. The suppression of VT induction did not correlate with the changes in QT, QTc, and ERP after nifekalant administration. There were no significant differences in induced VT cycle length at baseline study between responders and nonresponders to nifekalant. Reverse use dependence was not apparent on review of electrophysiologic parameters. Neither proarrhythmic events nor hemodynamic disturbances occurred after nifekalant administration. It was concluded that nifekalant could be used safely and showed comparable effectiveness to procainamide for the suppression of VT induction.

Adult↗
PubMed2002

Synthesis of 27-oxo, 27-hydroxymilbemycins A3 and A4 and novel 27-alkoxymilbemycins A3 and A4 from milbemycins A3 and A4 and their acaricidal activities.

27-Oxomilbemycins A3 and A4 and 27-hydroxymilbemycins A3 and A4 were identified as metabolites in soil metabolism studies of milbemycins A3 and A4. Chemical derivation methods were developed to synthesize 27-oxomilbemycins A3 and A4 and 27-hydroxymilbemycins A3 and A4 from milbemycins A3 and A4. In addition, 27-alkoxymilbemycin derivatives were also synthesized from the same precursors. Some of the synthesized compounds displayed satisfactory acaricidal activity against the organophosphorus-sensitive two-spotted spider mite (Tetranychus urticae), but did not have superior activity to corresponding milbemycins A3 and A4.

Anthelmintics↗